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Fragmentation of isolated populations increases the risk of inbreeding and loss of genetic diversity. The endemic Saimaa ringed seal (Pusa hispida saimensis) is one of the most endangered pinnipeds in the world with a population of only ~ 400 individuals. The current genetic diversity of this subspecies, isolated in Lake Saimaa in Finland for ca. 1000 generations, is alarmingly low. We performed whole-genome sequencing on Saimaa ringed seals (N = 30) and analyzed the level of homozygosity and genetic composition across the individual genomes. Our results show that the Saimaa ringed seal population has a high number of runs of homozygosity (RoH) compared with the neighboring Baltic ringed seal (Pusa hispida botnica) reference population (p

Host-specialist parasites of endangered large vertebrates are in many cases more endangered than their hosts. In particular, low population densities and reduced among-host transmission rates are expected to lead to inbreeding within parasite infrapopulations living on single host individuals. Furthermore, spatial population structures of directly-transmitted parasites should be concordant with those of their hosts. Using population genomic approaches, we investigated inbreeding and population structure in a host-specialist seal louse (Echinophthirius horridus) infesting the Saimaa ringed seal (Phoca hispida saimensis), which is endemic to Lake Saimaa in Finland, and is one of the most endangered pinnipeds in the world. We conducted genome resequencing of pairs of lice collected from 18 individual Saimaa ringed seals throughout the Lake Saimaa complex. Our analyses showed high genetic similarity and inbreeding between lice inhabiting the same individual seal host, indicating low among-host transmission rates. Across the lake, genetic differentiation among individual lice was correlated with their geographic distance, and assignment analyses revealed a marked break in the genetic variation of the lice in the middle of the lake, indicating substantial population structure. These findings indicate that movements of Saimaa ringed seals across the main breeding areas of the fragmented Lake Saimaa complex may in fact be more restricted than suggested by previous population-genetic analyses of the seals themselves.

Site fidelity is commonly observed in pinnipeds and has direct consequences for individual space use and population dynamics. Here, we used photo-identification recapture data to quantify site fidelity of the endangered Saimaa ringed seal (Pusa hispida saimensis) over four successive moulting seasons. We identified 337 seals based on their permanent fur patterns, and 192 of them were observed during at least 2 years. Over the study period, the median number of terrestrial haul-out sites used by an individual seal was four, and nearly 50% of the seals reused them over the years. Although eight seals performed movements (up to 48 km) between the different water basins of Lake Saimaa, most of the studied seals remained in the same water basin over the years. The median distance between successive moulting sites used by an individual seal was 643 m. While these distances were similar within years in both sexes, the distances between years were longer in females, suggesting post-nursing related behaviour. The extreme site fidelity of the Saimaa ringed seal has important implications for its conservation, especially in the land use management of the Lake Saimaa shoreline.

AimThe Saimaa ringed seal (Pusa hispida saimensis) is endemic to Lake Saimaa in Finland. The subspecies is thought to have originated when parts of the ringed seal population of the Baltic region were trapped in lakes emerging due to post-glacial bedrock rebound around 9,000 years ago. During the 20th century, the population experienced a drastic human-induced bottleneck. Today encompassing a little over 400 seals with extremely low genetic diversity, it is classified as endangered. Our main aim was to evaluate the role of the 20th century bottleneck in the erosion of genetic diversity in the Saimaa seal population. We also evaluated connections with other ringed seals from the Baltic Sea, Lake Ladoga, North America, Svalbard and the White Sea.LocationLake Saimaa, Finland, together with the Baltic Sea and the Arctic Ocean.MethodsWe sequenced sections of the mitochondrial control region from 60 up to 125 years old museum specimens of the Saimaa ringed seal. The generated dataset was combined with publicly available sequences. We studied how genetic variation has changed through time in this subspecies, and how it is phylogenetically related to other ringed seal populations.ResultsWe observed temporal fluctuations in haplotype frequencies and loss of haplotypes accompanied by a recent reduction in female effective population size. In apparent contrast with the traditionally held view of the Baltic origin of the population, the Saimaa ringed seal mtDNA variation shows also affinities to North American ringed seals.Main conclusionsOur results suggest that the Saimaa ringed seal has experienced recent genetic drift associated with small population size. The results further suggest that extant Baltic ringed seals do not represent well the ancestral population of the Saimaa ringed seal, which calls for re-evaluation of the deep history of this subspecies.

Fragmentation of isolated populations increases the risk of inbreeding and loss of genetic diversity. The endemic Saimaa ringed seal (Pusa hispida saimensis) is one of the most endangered pinnipeds in the world with a population of only ~400 individuals. The current genetic diversity of this subspecies, isolated in Lake Saimaa in Finland for ca. 1,000 generations, is alarmingly low. The population is further divided into semi-isolated subpopulations in the labyrinthine landscape of the lake, which exposes the population to deleterious genomic effects. We performed whole-genome sequencing on Saimaa ringed seals (N=30) and analyzed the level of homozygosity and genetic composition across the individual genomes. Our results show that the Saimaa ringed seal population has a high number of runs of homozygosity (RoH) compared with the neighboring Baltic ringed seal (Pusa hispida botnica) reference population (p

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Incidental bycatch, mostly in gillnets used for recreational fishing, is a critical mortality factor for the Endangered Saimaa ringed seal Pusa hispida saimensis. Bycatch particularly affects juveniles, and therefore fishing has been restricted by banning gillnets during the most critical juvenile dispersal period in spring. In addition, the most harmful gear types for ringed seals of all ages are forbidden year-round. The springtime restriction areas have increased significantly since the 1990s, now covering over 90% of the pups’ birth sites. However, the impacts of fishing restrictions on incidental bycatch mortality have not previously been evaluated statistically. The present estimates of incidental bycatch levels in relation to fishing restrictions since the 1990s suggest that the springtime gillnet fishing ban resulted in an increase in population size by 20% between 1991 and 2013 (60 individuals given an average estimated stock size of 355 in 2013). In addition, the estimated critical period for juvenile survival in relation to fishing operations appeared to be the first 15 mo, which is a much longer time than previously expected, suggesting that stationary gillnet fishing during late winter months may cause a secondary peak in seal mortality. One unwanted estimated side effect of the seasonal ban was a slightly increased incidental estimated bycatch level immediately after the end of the springtime fishing restriction period. The estimated bycatch peaked in 2000-2005, with an average of 13.3 juveniles annually and decreased thereafter, mainly in 2009-2013, with an average of 6.3 juveniles annually.

Taiga bean goose (Anser fabalis fabalis) is an endangered subspecies that breeds sporadically in remote habitats in the arctic and boreal zones. Due to its elusive behaviour, there is a paucity of knowledge on the behaviour of taiga bean goose during the breeding season, and survey methods for monitoring numbers in the breeding areas are lacking. Camera traps are a useful tool for wildlife monitoring, particularly when there is a need for non-invasive methods due to the shy nature of the species. In this study, we tested the use of camera traps to investigate seasonal and diel activity patterns of taiga bean goose in Finland over two successive breeding seasons, 2018 and 2019. We did this by modelling counts of geese from images with generalized linear and additive mixed models. The camera type (cameras placed by experts specialized in bean goose ecology vs randomly placed cameras) did not influence the count of taiga bean goose (p = 0.386). However, the activity varied significantly by region, Julian day, time of day and temperature, with the study site (individual peatland) and year adding substantial random variation and uncertainty in the counts. Altogether, the best fitting model explained nearly 70% of the variation in taiga bean goose activity. The peak in activity occurred about a month later in the southernmost region compared to the more northern regions, which may indicate behaviours related to migration rather than breeding and moulting. Our results show that long-term monitoring with game camera traps provide a potential unobtrusive approach for studying the behavioural patterns of taiga bean goose and can increase our ecological knowledge of this little-known subspecies. The results can be applied to planning of the annual censuses and finding the optimal time frame for their execution.

Climate change enables expansion of southern species whereas many boreal species retreat northwards. Range shifts create novel interactions that can affect abundance and distribution via competition and/or hybridization. It is possible that the mountain hare (Lepus timidus) long-term decline in northern Europe is linked to competition with the brown hare (L. europaeus). In order to understand consequences of hare interactions at high latitudes, we determined geographical extent of hybridization using mitochondrial DNA (mtDNA) introgression as a proxy. Additionally, we compared species distribution and snow conditions in Finland with introgression frequency. We found that introgression is bidirectional but direction is mostly from the mountain hare to the brown hare. Approximately 10% of brown hares have introgressed mtDNA, being most common at the northern expansion front of their distribution range. Introgression is likely linked to brown hare expansion facilitated by climate change, but due to complex n...

The effective size of a population (Ne), which determines its level of neutral variability, is a key evolutionary parameter. Ne can substantially depart from census sizes of present-day breeding populations (NC) as a result of past demographic changes, variation in life-history traits and selection at linked sites. Using genome-wide data we estimated the long-term coalescent Ne for 17 pinniped species represented by 36 population samples (total n = 458 individuals). Ne estimates ranged from 8,936 to 91,178, were highly consistent within (sub)species and showed a strong positive correlation with NC ( $${R}_{\mathrm{adj}}^2$$ = 0.59; P = 0.0002). Ne/NC ratios were low (mean, 0.31; median, 0.13) and co-varied strongly with demographic history and, to a lesser degree, with species’ ecological and life-history variables such as breeding habitat. Residual variation in Ne/NC, after controlling for past demographic fluctuations, contained information about recent population size changes during the Anthropocene. Specifically, species of conservation concern typically had positive residuals indicative of a smaller contemporary NC than would be expected from their long-term Ne. This study highlights the value of comparative population genomic analyses for gauging the evolutionary processes governing genetic variation in natural populations, and provides a framework for identifying populations deserving closer conservation attention. Using comparative population genomics across pinnipeds, this study explores how demographic change and life-history traits are correlated to the effective size of a population and conservation status.

Photo-identification (photo-ID) with camera traps was examined as a non-invasive method for studying and monitoring the endangered Saimaa ringed seal Phoca hispida saimensis. An average of 51 game cameras were set up at shoreline haul-out sites in central Lake Saimaa during the moulting seasons in each of the years from 2010 to 2014. Individuals were identified from their lifelong unique lateral fur patterns. A total of 220 000 digital images of seals were obtained from these game cameras and from digital cameras during this period, allowing 164 indi- viduals to be identified, 43% of which were re-sighted in successive years. In the majority of game camera images, both sides of the seal were shown, and it was possible to determine the sex of the seal. The average distance between sightings of individual seals in different years was 1.6 km, suggesting that Saimaa ringed seals exhibit a high degree of moulting site fidelity. In addition, the results support suggestions of natal site fidelity. We propose that photo-ID sampling based on camera traps, and larger-scale photographic survey of the seals, should be implemented as a pop- ulation monitoring tool of the Saimaa ringed seal. Further application of the photo-ID technique may facilitate mark-recapture population and survival rate estimates for this threatened seal spe- cies and provide significant insights into its life history and social behaviour.

Western European hedgehogs (Erinaceus europaeus) are commonly found in urban environments. To evaluate human-hedgehog interactions on the northern margin of the hedgehog range, we investigated the causes of mortality, the occurrence of diseases, parasites and bacterial infections, and the diet of hedgehogs (males n = 87, females n = 66, sex unknown n = 100) found dead in Joensuu, Finland, during the years 2004–2005. Hedgehog carcasses were obtained from a radio telemetry tracking study and a traffic mortality survey conducted by us, as well as from local people who provided us with dead hedgehogs. Of the carcasses obtained during the tracking study, 75 % died of human-related causes. The vast majority (97 %) of human-related deaths were road kills, and more than half (56 %) of natural deaths were by starvation. The average number of hedgehogs killed on the roads was 0.65 per 100 km of road transect studied. Purulent and gangrenous inflammation of the limbs was found in 11 adult males (out of 38 collected) in pathological examinations. The Salmonella enteritidis (phage type 20) infections that were found in 57 % of the individuals examined were typically latent and were mainly found in the liver. Lungworms (Crenosoma striatum) were found in 79 % of the individuals examined. Altogether, 92 % of the stomachs contained remains of human foods, especially fish and milk. The hedgehogs’ natural diet included invertebrates such as beetles (Coleoptera) and earthworms (Clitellata). Our results show that the main negative anthropogenic impact on hedgehogs is severe traffic mortality. The observed high prevalence of Salmonella calls for appropriate hygienic measures when feeding and handling hedgehogs.

We tested the use of unmanned aerial systems (UAS) in duck brood surveys in boreal wetlands in Finland. We performed brood surveys at the same wetlands concurrently with ground-based point counts and using a UAS (multicopter; drone counts) equipped with a camera that produced high-quality images for identification of broods and ducklings. The number of broods did not differ between point counts and drone counts in three duck species, the mallard (Anas platyrhynchos), common teal (Anas crecca), and common goldeneye (Bucephala clangula). The number of ducklings was higher in drone counts than in point counts in the common teal, but no such difference was found in the mallard and common goldeneye. UAS-based images seem to be useful for estimating numbers of both broods and ducklings for different duck species, although the manual processing of images is labor intensive.

Movement is a fundamental element of animal behaviour, and it is the primary way through which animals respond to environmental changes. Therefore, understanding the drivers of individual movement is essential for species conservation. The endangered Saimaa ringed seal (Phoca hispida saimensis) lives land-locked in Lake Saimaa and is affected by various anthropogenic factors. Telemetry studies provide critical information but are insufficient to identify the mechanisms responsible for particular movement patterns. To better understand these mechanisms and to predict how changed movement patterns could influence the subspecies’ spatial ecology, we developed an individual-based movement model. We divided the seals’ daily routines into foraging and resting and explored how well the model captured observed home ranges and other movement metrics. Here we present the model, its predictions of home ranges and its sensitivity to model assumptions and parameter uncertainty. We used movement data from one individual to calibrate the model, but this resulted in poor predictions of home range sizes of five seals used for validation. This suggests that differences in movement paths not only reflect different landscape configurations but also differences among the individuals’ state and personalities. Therefore, we separately re-calibrated the model to data from five individuals, reproducing their home ranges, habitat use and movement paths more accurately. Although ignoring many aspects of seal behaviour, the model can be applied as a tool to guide further data collection and analysis, study seal ecology, and evaluate the efficacy of various conservation measures.

The endangered Saimaa ringed seal (Pusa hispida saimensis) is exposed to relatively high concentrations of mercury (Hg) in freshwaters poor in selenium (Se), a known antagonist of Hg. The impact of age and sex on the bioaccumulation of Hg and Se was studied by analyzing liver, muscle, and hair samples from seals of different age groups. Adult females were found to accumulate significantly more Hg in the liver (with ca. 60% as HgSe), and less Hg in the muscles compared to adult males, which may be explained by accelerated metabolism during gestation and lactation. In adult seals, molar Se:Hg ratios in the muscles fall below one, which is considered a threshold for the emergence of adverse effects. As a result, Saimaa ringed seals may be at risk of developing health and reproductive problems. According to mass balance calculations, the pups are exposed to considerable amounts (μg/d) of mercury during gestation, although lactation is their main exposure route. In lanugo pups, Hg concentrates in the hair, and molting serves as a main detoxification route. For other age groups, demethylation followed by the formation of HgSe is the main detoxification route, and the demethylation capability develops in pups by the time of weaning.

Morphometrics and growth of the critically endangered Saimaa ringed seal (Pusa hispida saimensis), which inhabits a freshwater lake in Finland were studied using data from 344 carcasses. This study presents the first detailed information on ringed seal pup growth and body condition from birth to the age of one year. Newborn pups were on average 68 cm long and weighed 5 kg. Pups attained the majority of their first year growth during the nursing period. Body condition and growth declined after weaning, but pups recovered from postweaning nutritional deprivation at the age of 8 mo. The seals achieved their maximum body length, girth, and mandible size around the age of 4 yr, and asymptotic body mass two years later. Baculum growth indicated that males reached sexual maturity at age 5–6 yr. The Saimaa ringed seals' asymptotic body length and mass were 132 cm and 59 kg, respectively, which is similar to medium sized marine ringed seals. Saimaa ringed seals' survival to adulthood is extremely low due to high bycatch mortality; furthermore climate change may hamper pup growth and elevate mortality. Therefore we recommend continuation of fishing closures to improve pup survival.

Genetic analyses of non-invasively collected samples are increasingly being used in the monitoring of wildlife populations and individuals. This study is the first describing the use of placentas as non-invasive genetic samples from a natural population. We collected 66 placentas from birth-lair sites of Saimaa ringed seals (Phoca hispida saimensis) after the breeding seasons, with the aim of obtaining DNA from both the pup and the mother. Umbilical cord samples proved to yield the pup genotypes, but mothers could not be genotyped with confidence. Comparisons with existing mtDNA and microsatellite reference data sets showed that placentas can be used for inferring population-level genetic parameters. Our microsatellite panel provided sufficient resolution for genetic identification of individuals but, due to the extremely low variability of the population, parentage and sibship could not be inferred reliably. Field-collected placentas could provide means for genetic monitoring of many other seal species a...

The increasing Baltic grey seal (Halichoerus grypus) population causes considerable damage to coastal fisheries. The aim of the present study was to compare the age, sex and blubber thickness of seals that cause problems to coastal fisheries (i.e. by-catch seals and those shot near the fishing gear) with those killed during regular hunting. This knowledge is essential for population management. We collected seal samples from hunters and fishermen from Finland, Sweden and Estonia in 2011–2013. Hunted seals included individuals of all age classes, whereas most by-catch seals were small pups (in spring) or sub-adult and adult males (in autumn). By-catch seals had a thinner blubber layer than hunted seals. Most seals shot near the fishing gear were adult males in good condition. The ‘problem seals' were thus not a random sample of the population. We suggest that hunting should be targeted especially at males to mitigate the damage to fisheries without threatening the population.

The Saimaa ringed seal (Pusa hispida saimensis) is one of the few freshwater seal populations worldwide. The major conservation issue of this critically endangered population is bycatch mortality. We used digestive tract content and stable isotopes (d 13 Ca ndd 15 N) to estimate the diet and seasonal feeding patterns for gaining better understanding of the seals feeding habits and potential conservation implications. The diet was similar across age groups. Altogether 15 fish species were identified and the most important were smelt (Osmerus eperlanus), ruff (Gymnocephalus cernuus), perch (Perca fluviatilis), vendace (Coregonus albula )a nd cyprinids. The high d 15 N values suggested that the seals lose weight during winter and spring. Additionally the drop in d 15 N values indicated that pups start to recover from postweaning stress and gain weight around the age of 6 mo. The isotope values differed regionally, which emphasizes that samples from consumers and prey should be collected from the same regions to improve interpretation of the stable isotopic results. Overall, diet composition suggests minimal to nonexistent competition with commercial or recreational fishing. However, observed weight loss of pups during summer may be related to higher risk of bycatch and this should be taken into account when planning temporal fishing closures.

The ringed seal (Phoca hispida) is dependent on sufficient ice and snow cover for a breeding habitat. Therefore, climate change has a negative effect on pup survival. We developed methods to estimate perinatal mortality and to mitigate the effects of mild winters on the critically endangered subspecies (P. h. saimensis). Underwater surveys were used for collecting pup carcasses and placentas. Lanugo pup mortality was 13.5% and Brucella sp. was not found in the placentas. Camera traps showed sporadic human and medium-sized carnivore activity in the breeding habitat. Although carnivore activity was most intensive at lair sites, no penetration of the lairs was observed. We developed a method to mitigate the effects of poor snow cover by piling up snowdrifts (n = 117) at potential lair sites. Seals subsequently occupied 62% of these snow drifts. We suggest that the methods developed in this study should be implemented to conserve the Saimaa ringed seal.

Human disturbance can affect the viability of wildlife populations partly through its effects on breeding success. Land use as a form of disturbance may do so by fragmenting the key environments of certain species. We used statistical pattern recognition methods to estimate the long-term effects of human disturbance on the Endangered, landlocked population of the Saimaa ringed seal Pusa hispida saimensis by examining how various densities of buildings on lake shores have altered the survival of juveniles and the persistence of the population. In addition, we examined whether disturbance caused by different intensities of land use would further reduce the long-term persistence of the population. We also provide estimates of the quality of Lake Saimaa shorelines as breeding habitat in relation to building density. Our results show that at present, the lairs of Saimaa ringed seals are located closer to potential sources of human disturbance than they were in the past and that land use intensity has an effect on juvenile mortality. Perinatal mortality increases significantly in more densely developed areas, where the nearest building is within 800 m of a birth lair. In addition, 29% of the shoreline of Lake Saimaa is no longer suitable for ringed seals due to intensive land use. Our results illustrate how human disturbances can significantly compromise juvenile survival and therefore the long-term existence of this Endangered population., published version, peerReviewed

Island populations are on average smaller, genetically less diverse, and at a higher risk to go extinct than mainland populations. Low genetic diversity may elevate extinction probability, but the genetic component of the risk can be affected by the mode of diversity loss, which, in turn, is connected to the demographic history of the population. Here, we examined the history of genetic erosion in three Fennoscandian ringed seal subspecies, of which one inhabits the Baltic Sea ‘mainland’ and two the ‘aquatic islands’ composed of Lake Saimaa in Finland and Lake Ladoga in Russia. Both lakes were colonized by marine seals after their formation c. 9500 years ago, but Lake Ladoga is larger and more contiguous than Lake Saimaa. All three populations suffered dramatic declines during the 20th century, but the bottleneck was particularly severe in Lake Saimaa. Data from 17 microsatellite loci and mitochondrial control-region sequences show that Saimaa ringed seals have lost most of the genetic diversity present in their Baltic ancestors, while the Ladoga population has experienced only minor reductions. Using Approximate Bayesian computing analyses, we show that the genetic uniformity of the Saimaa subspecies derives from an extended founder event and subsequent slow erosion, rather than from the recent bottleneck. This suggests that the population has persisted for nearly 10,000 years despite having low genetic variation. The relatively high diversity of the Ladoga population appears to result from a high number of initial colonizers and a high post-colonization population size, but possibly also by a shorter isolation period and/or occasional gene flow from the Baltic Sea.

During the period 2000–2012 we witnessed a general increase in the Baltic grey seal (Halichoerus grypus) population size. Population growth has, however, ceased in the northern sea areas. The accompanying changes to age structure during this time suggest a reduced female pregnancy rate. In this study, we used hunted individuals to examine the ovulation and pregnancy rates of seals from different age classes and years. We examined the presence of corpus luteum, corpus albicans and placental scars from seals killed before the implantation period and fetuses after the implantation period. The pregnancy rate derived from the presence of corpus albicans or placental scars in the pre-implantation period was similar to that based on fetuses. Thirty-three percent of females ovulated at the age of 3 years, 81% at the age of 4 years and 99% thereafter. The pregnancy rate was lower among 4–5-year-old females (0.54–0.56) than among 6–24-year-old females (0.77–0.86), being highest in 7–11-year-old females. The pregnan...

Many species shift their distribution northwards due to changing climate, which may bring previously isolated species into contact. In some cases, this can lead to competition and crossbreeding among congeneric species. Due to milder winters, several hare species (Lepus spp.) have shifted poleward or to higher elevations and currently occur in sympatry. There are limited data on the spatial ecology of northern brown hares (L. europaeus), and on possible joint space use with mountain hares (L. timidus), although species are known to frequently crossbreed. We estimated home ranges of 12 brown and 12 mountain hares in eastern Finland using GPS telemetry. The total home-range median areas were 111 ha for brown hares and 105 ha for mountain hares. The median core areas of these species were 5 and 3 ha, respectively. Individual home ranges and core areas of the studied species overlapped. Interspecific interaction seems to be frequent during the breeding season, which also enables crossbreeding.

Conservation of the Critically Endangered ringed seal Phoca hispida saimensis pop- ulation in Lake Saimaa in Finland requires broader knowledge of the behavioural ecology of this subspecies. Understanding Saimaa ringed seal haulout patterns and their response to boat traffic is crucial for designing sustainable land use and tourism guidelines. Responses of unidentified seals to small outboard motor boat traffic were studied during the moulting season. The median distance at which the seals responded to an approaching boat was 240 m. GPS-phone tags were used to study both circadian and seasonal haulout behaviour patterns of individual seals (n = 8) during the open-water season. The average post-moulting haulout duration was 6 ± 5 h (SD), with a maximum of over 26 h. The seals spent more time hauled out at night (between 21:00 and 06:00 h) after the moult. The time spent hauled out and the haulout frequency declined from early summer to autumn. An individual seal had an average of 13 haulout sites, which were an average of 2.5 km apart. Approximately half of these haulout sites were located in the core 50% of the indi- vidual seals' home ranges. The high level of site fidelity emphasizes the need to identify suitable haulout areas and to develop measures for protecting the main resting sites of this endangered population. Additionally, guidelines for seal watching should be developed in order to mitigate the potential disturbance caused by increasing tourism on Lake Saimaa.

Little information exists on the nesting of hedgehogs (Erinaceus europaeus) in the harsh northern environment, although this aspect has specific importance for the species’ survival in this region. We studied the nest types and nesting site selection of radio tagged hedgehogs in urban areas in Eastern Finland. Altogether, four different nest types were discovered and one of them (the pre-hibernation nest) is described here for the first time. Hedgehogs preferred residential areas for nesting during the mating and post-mating seasons while in the pre-hibernation season and hibernation period nesting was more common in forest areas. Nest constructions were closely related to materials found in the nest vicinity. During the active period, males used on average 24 nests and changed them 30 times, whereas females used 17 nests and changed them 26 times. The number of female nests and frequency of nest change increased from post-mating to pre-hibernation seasons, while in males both decreased. In general, female and male nests were situated within their established long-term home range, but in the pre-hibernation season over 30 % of male nests were situated outside of it. In post-mating and pre-hibernation seasons, females avoided other individuals of the same sex; this was demonstrated by the lack of nests in other female core areas. Hedgehogs hibernate for around 223 days, which is the longest reported hibernation period for this species. The results of the present study emphasise the importance of forest and diverse residential areas including forest patches for the hedgehog’s nesting habitat.

Limited data exist on ecology of European hedgehog (Erinaceus europaeus) at the northern edge of the species’ range. In our study, spatial analysis using radio-tracking data from Finland showed that sex and season had significant effects on the homerange size of hedgehogs. Although males were heavier than females, body weight had no effect on home-range size. Total home ranges (male 98, female 55 ha) were larger than those in southern areas. Thus, male home ranges were larger than those of females during the mating (male 72, female 21 ha) and post-mating seasons (male 48, female 20 ha), but the differences were small and reversed before hibernation (male 17, female 29 ha). Home ranges of individuals of both sexes overlapped, but females shared core areas with other females only during the mating season. Our results imply possible differences in hedgehog ecology probably due to a less productive and harsh northern habitat.

Bycatch mitigation is currently the most important issue for conservation of the Critically Endangered Saimaa ringed seal Phoca hispida saimensis found exclusively in Lake Saimaa, Finland. Two types of fishing restrictions have been established in order to reduce mortality: a ban on gillnet fishing during the most critical season (spring) to enhance pup survival and a yearround ban on the types of fishing gear most likely to cause seal mortality (e.g. certain specified fish traps, hooks baited with fish, strong-mesh gillnets, multifilament nets and trammel nets). The spatial and temporal coverage of these restrictions has not always been based entirely on the ecology and movements of the seals. The current distribution area of the population is not fully known, and this hampers the assessment of conservation needs. In this study, adult Saimaa ringed seals were tracked with GPS phone tags to estimate home ranges and movements. In addition, pup movement data from VHF telemetry studies were used to determine current breeding areas and nursing sites. The mean home ranges of both adults and pups were around 90 km2. The current distribution area of the seals covers about 70% of the surface area of Lake Saimaa (4400 km2), and the breeding area covers about 51%. The current springtime fishing restriction covers 63% of the estimated distribution area, and the restriction on fishing gear types covers 55%. This new information on the spatial ecology of Saimaa ringed seals should be used to improve efforts to conserve the species.

We examined the demographic structure and mortality rate of the Baltic grey seal (Halichoerus grypus) population from the early 2000s when the population increased rapidly to the late 2000s when the growth rate slowed down. We calculated life tables based on the age structure of hunted grey seals in the Finnish sea area. The catch was treated as a sample of the dying part of the population. The catch was male biased and the proportions of female pups and mature males in the catch increased from the early to late 2000s. Annual mortality rate of the youngest age classes was high and higher among males than females, which resulted in low sex ratio (males to females) of the population. Sex ratio was, however, higher in the latter years due to the increased mortality rate of females, especially those < 10 years of age. Accordingly, the proportion of mature females in the population decreased and relatively fewer pups were produced during the late 2000s than in the early 2000s.

Molecular-genetic assessments of demographic history, population structure, and loss of genetic variation in small natural populations are often hampered by a lack of information on initial diversity, isolation time, and migration rates. The landlocked population of currently less than 300 ringed seals inhabiting Lake Saimaa in southeastern Finland offers a unique model for studying these questions in small populations. It has remained completely isolated since the last ice age, information on its initial genetic diversity can be inferred from the large marine source population in the Baltic Sea, and its ecology is well studied. We analyzed the mitochondrial DNA diversity of 215 Saimaa ringed seals spanning three decades in order to assess long- and short-term changes in the gene pool of this critically endangered subspecies. The mtDNA diversity of the Saimaa ringed seal is low, consisting of only eight haplotypes. Nevertheless, coalescent simulations show that the diversity is unexpectedly high when contrasted with the over 800 generations of isolation and the estimated historical carrying capacity of the lake. In the short term, marked temporal and spatial differentiation was observed among three decades and four regions of Lake Saimaa, suggesting extremely low effective subpopulation sizes and limited migration of females within the lake. Our study strongly suggests that enhancing gene flow and population growth is crucial for maintaining the remaining genetic diversity of the Saimaa ringed seal.

We investigated the vertical stratification pattern of fatty acids in the blubber of the freshwater Saimaa ringed seal ( Phoca hispida saimensis ; n = 35). Blubber was dissected vertically into 3 mm thick sequential subsamples, and the fatty acid composition was analyzed separately for each subsample. The combined vertical fatty acid profiles (expressed as numerical gradients) showed that the blubber of > 1 year old individuals is stratified into three distinguishable layers: superficial (~ 1.5 cm), middle and deep (~ 1 cm). Thickness of the middle layer varied according to the total blubber thickness. We suggest that the observed layering is related to the differences in the tissue temperatures and metabolic activity in the blubber column. The dissimilarity in the fatty acid composition (measured as Euclidean distance) between the different blubber layers and the 5 most important fish prey species available in Lake Saimaa was largest in the superficial blubber. In fact, the fatty acid composition of superficial blubber resembled more that of marine ringed seal ( Phoca hispida hispida ) blubber than any of the analyzed fish species. The composition closest to that of the prey was found in the deep blubber of the Saimaa ringed seal. The large vertical differences in the fatty acid composition of blubber lipids, which likely affect the vertical distribution of other endogenous or exogenous lipophilic substances as well, will set conditions for the sampling of blubber for biomonitoring and dietary studies. Thus the knowledge on the potential layers with different composition and the depths they span in different individuals (e.g. young versus old; with thin versus thick blubber) is crucial for improving the validity and reliability of monitoring methods utilizing the blubber tissue.

Lake Saimaa in eastern Finland is inhabited by a critically endangered ringed seal subspecies Pusa hispida saimensis. Since accidental mortality in gill nets, resulting in reduced pup survival, is considered to be the main factor contributing to the decline in its population, fishing restriction areas have been established. In this study, 10 pups were located daily using very high frequency (VHF) telemetry to estimate their home ranges, movements, and survival. The pups dispersed after weaning at the age of ca. 3 mo and moved up to 15 km a day between consecutive locations and up to 25 km away from their birth sites. The home ranges of the pups at the age of 3–4 mo were variable in size, from 3 to 162 km2. The pups preferred the same shallow water areas (

Population structure and patterns of habitat use among ringed seals (Phoca hispida) are poorly known, in part because seasonal movements have not been adequately documented. We monitored the movements of 98 ringed seals in the Beaufort and Chukchi seas between 1990 and 2006 using three forms of telemetry. In the winter—spring period (when the seals were occupying shorefast ice), we used radio and ultra-sonic tags to track movements above and below the ice, respectively. We used satellite-linked transmitters in summer and fall (when the seals ranged away from their winter sites) to track at-sea movements. In the shorefast ice habitat, the home ranges of 27 adult males ranged from \1 to 13.9 km 2 (median = 0.628) while the home ranges of 28 adult females ranged from \ 1t o 27.9 km 2 (median = 0.652). The 3-dimensional volumes used by 9 seals tracked acoustically under the ice averaged 0.07 (SD = 0.04) km 3 for subadults and adult males and 0.13 (SD = 0.04) km 3 for adult females. Three of the radio-tracked seals and 9 tracked by satellite ranged up to 1,800 km from their winter/spring home ranges in summer but returned to the same small (1-2 km 2 ) sites during the ice-bound months in the following year. The restricted movements of ringed seals during the ice-bound season— including the breeding season—limits their foraging activities for most of the year and may minimize gene flow within the species.